Default formatter under Linux fdisk doesnt format partitions more than 2TB. Workaround is described below.

Solution

Enter a shell script, and type: parted /dev/sda or wahever drives need to be formatted

We will have to make the label for the partition.At the (parted prompt, type:

(parted)mklabel gpt <enter>

The disk geometry for your disk array will be displayed.

Next type:

(parted)p <enter>

This will show you the disk geometry in megabytes for your array (/dev/sda). In your case it would show:

Disk geometry for /dev/sda: 0.000-4800GB

(parted) mkpartPartition type? [primary]? primaryFile system type? [ext2]? ext2Start? 0End? 4800The partition is now created. You can use mkfs to format it.

(parted)mkfs 1 /dev/sda1).

(parted)q

Note: When you use parted to display the partition size (e.g. the p command in parted), it will show an incorrect value for the 'End'. However, the 'Disk geometry' will be displayed correctly.

This would be the display for a 4.3 TByte array with parted:

(parted) p

Disk geometry for /dev/sda: 0.000-4800GB

Disk label type: gpt

Minor Start End Filesystem Name Flags

1 0.017 525335.983 ext3

The '4800' value is correct for GB, but the '525335.983' is incorrect for the End value (it is too small).

After doing this we have to make the partition ext3 as parted doesnt support ext3.

# tune2fs -j /dev/sda2

And you are done. Dont forget to make entries in the fstab file to mount the new made filesystem.

]]>Problem

How to mount SCSI devices without rebooting the machine.

Solution

WORKAROUND.

Working with (SCSI) devices;

/proc/scsi

/proc/scsi/scsi

How to add more disk space if you have hot-swap drives available to you, without rebooting the system. Without using /proc, you could insert your drive, but you would then have to reboot in order to get the system to recognize the new disk. Here, you can get the system to recognize the new drive with the following command:

echo "scsi add-single-device w x y z" > /proc/scsi/scsi

For this command to work properly, you must get the parameter values w, x, y, and z correct, as follows:

w is the host adapter ID, where the first adapter is zero (0)

x is the SCSI channel on the host adaptor, where the first channel is zero (0)

y is the SCSI ID of the device

z is the LUN number, where the first LUN is zero (0)

Once your disk has been added to the system, you can mount any previously formatted filesystems or you can start formatting it, and so on. If you are not sure about what device the disk will be, or you want to check any pre-existing partitions, for example, you can use a command such as fdisk -l, which will report this information back to you. Conversely, the command to remove a device from your system without a reboot would be:

echo "scsi remove-single-device w x y z" > /proc/scsi/scsi

]]>ProblemHow to increase Read performance under Linux on 3ware controllers.

SolutionFor the Linux 2.4 kernel:Tuning Linux VM parameters may help to increase the read performance, depending your RAID type, application, and other factors. You can try this setting and see if it helps increase performance in your situation.

The settings are: To make the change without having to reboot (change will not survive after a reboot), type the following from a command prompt: